Question 1

Which of the following statements best explains why Archaea are more closely related to Eukarya than to Bacteria?

Accepted Answer

Archaea and Eukarya share histones and similar ribosomal proteins, unlike Bacteria.

Question 2

A scientist discovers a microorganism living in a hot spring with temperatures above 80°C and a pH of 2. Which term best describes this organism?

Accepted Answer

Thermophile

Question 3

Which process allows bacteria to acquire new genetic material directly from their environment?

Accepted Answer

Transformation

Question 4

A bacterium is classified as a chemoautotroph. Which of the following best describes its nutritional mode?

Accepted Answer

It uses chemical energy and inorganic compounds as a carbon source.

Question 5

Which of the following equations correctly represents the process of nitrogen fixation performed by certain prokaryotes?

Accepted Answer

$N_2 + 8H^+ + 8e^- \rightarrow 2NH_3 + H_2$

Question 6

Which of the following best describes the ecological role of cyanobacteria in aquatic environments?

Accepted Answer

They are photoautotrophs that produce oxygen and fix nitrogen.

Question 7

A bacterium is found to be resistant to penicillin and stains pink in a Gram stain. What is the most likely explanation for this observation?

Accepted Answer

It has a thin peptidoglycan cell wall and an outer membrane.

Question 8

Which mechanism of horizontal gene transfer involves a virus as a vector for genetic material?

Accepted Answer

Transduction

Question 9

Which of the following best describes mutualism in prokaryotic symbioses?

Accepted Answer

Both organisms benefit from the association.

Question 10

A marine worm has no mouth, gut, or anus, yet survives by relying on bacteria inside its body. What type of symbiotic relationship is this?

Accepted Answer

Mutualism

Question 11

Which of the following is NOT a typical shape found among prokaryotes?

Accepted Answer

Cuboidal

Question 12

Which of the following best explains why prokaryotes are important in the global carbon cycle?

Accepted Answer

They act as both producers and decomposers, recycling organic and inorganic materials.

Question 13

Which of the following best describes an obligate anaerobe?

Accepted Answer

It cannot tolerate oxygen and may die in its presence.

Question 14

Which of the following is a real-world example of bacteria helping to solve environmental problems?

Accepted Answer

Bacteria breaking down PET plastic in landfills.

Question 15

Which of the following statements about horizontal gene transfer in prokaryotes is correct?

Accepted Answer

It is common and has played a major role in prokaryotic evolution.

Question 16

Which of the following best describes the role of nitrifying bacteria in the nitrogen cycle?

Accepted Answer

They convert $NH_3$ to $NO_2^-$ and $NO_3^-$, making nitrogen available to plants.

Question 17

Which of the following is a correct description of a halophile?

Accepted Answer

An organism that thrives in environments with high salt concentrations.

Question 18

Which of the following is a plausible consequence of the abundance of prokaryotes in municipal tap water (about $10^7$ bacteria/L)?

Accepted Answer

It can contribute to nutrient cycling and water quality, but most bacteria are harmless.

Question 19

Which of the following best explains the evolutionary origin of mitochondria and plastids in eukaryotes?

Accepted Answer

They originated from endosymbiosis with bacteria.

Question 20

A bacterium is described as a facultative aerobe. Which of the following best describes its oxygen response?

Accepted Answer

It can survive with or without oxygen.

Bacteria and Archaea: Diversity, Structure, and Ecological Roles

Study Guide - Practice Questions